[Eeglablist] removal of event-related (time/phase-locked) variance from ongoing oscillatory activity (cf. Makeig '93)

ramesh srinivar at uci.edu
Mon Dec 19 16:23:03 PST 2005

> My major concern is whether the assumptions underlying this regression
> procedure (or simple subtraction) are substantially violated by work
> showing interactions between event-locked and on-going oscillatory
> activity, such as phase re-setting or related phenomena. A related
> concern is whether the event-locked signal is likely to be stationary
> enough to allow this procedure to grab most of the event-locked
> variance?
> Any advice on these points would be gratefully appreciated!
> Alex

One thing to keep in mind, is that if there is a nonstationary mean 
value (u(t)) which is your EP,
the spectral estimates are invalid without removing it (whether or not 
there are interactions).
It seems to me what you have to do is apply one or the other procedures 
and evaluate your results for clues
for these mechanisms.  Phase-locking (rather than added signals) 
mechanisms are easy to detect.  Trial-to-trial
variability of the EP is more complicated.

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